1. Field of the Invention
The present invention relates to a rotary electric machine such as an AC generator for vehicle and a method for producing the rotary electric machine, in particular to a processing of a terminal of lead conductor of a stator.
2. Description of Background Art
A three-phase AC generator ordinarily having a rotor of a claw-like magnetic pole type is used for a generator equipped in a vehicle. The AC generator has a structure, for example, disclosed in Japanese Unexamined Patent Publication JP-A-4-168952, such that a three-phase stator coil is wound around a stator core on the stator side, the stator coil has lead conductors, a metallic terminal is attached to the ends of the lead conductors and connected and fixed to a three-phase full wave rectifier located on a bracket. The stator coil is, for example, a polyamide-imide electric wire, being a copper wire having an insulating coating of high heat resistance. The lead conductor is the copper wire, i.e. a single core copper wire elongated from the stator coil. The metallic terminal is made from a metal like copper and jointed to the lead conductor by soldering, caulking with soldering, fusing, or by an equivalent means thereto. The metallic terminal is fixed to the rectifier using a screw or the like.
A rotary electric machine such as an AC generator for vehicle is generally mounted on an engine frame inside an engine room of vehicle, where an atmospheric temperature is high and vibration applied to the engine is strong. In particular, under heavy load, the temperature of a stator coil becomes high by heat caused by generated electric current and the high atmospheric temperature. Therefore, when the lead conductor of the stator coil is jointed to the metallic terminal by soldering as described above, heat deterioration progresses, and the junction resistance of the jointed portion may increase to resultantly disconnect. To solve this problem, a use of a high temperature solder having a high Pb ingredient rate is inevitable. However, there are problems that the high temperature solder having the high Pb ingredient rate deteriorates working atmosphere and the reliability is lowered because workability becomes extremely unfavorable.
Further, the jointing by fusing has deficiencies that the shape of a jointed portion and the junction resistance are not stabilized because the jointed portion is welded with pressure applied, and fatigue breakdown is apt to occur by vibration generated by the engine. When the lead conductors and the metallic terminal are jointed only by caulking, the strength and the junction resistance are not stabilized. As a substitute, for example, a device described in Japanese Unexamined Patent Publication JP-A-10-4646, can be mentioned. In this device, a focused terminal and an enameled copper wire are subjected to pressure resistance welding using a brazing filler metal on a jointed surface between the focus terminal and the enameled copper wire. However, because the melt point of brazing filler metal is high, a large amount of heat is required at a time of jointing these, the press time is elongated, and large electric power is required. Therefore, there are problems such that a part of the insulating coat which is unnecessary to remove by peeling is destroyed, whereby insulation is deteriorated and the strength and the vibration proof are deteriorated by the heat deterioration of a copper wire. Further, because the focused terminal is not entirely wrapped by the brazing filler metal or the like, rust is easily produced. Further, there are problems such that the productivity is deteriorated and the dimensions after welding are not stabilized because the focused terminal is not in a tubular form and therefore it is necessary to hold the copper wire before the welding. Thus this conventional technique is not always suitable as a jointing method for an AC generator for vehicle.